Which is what I said in an earlier post.
It would depend on the condition of the rooms above as to which was the easier method. When I considered it the house was empty, and removing an entire floor from one room wouldn't have been as difficult as it might first seem.
I hadn't heard of your method, though, and nor was it suggested at the time.
Unfortunately, the area where the beam is to be installed spans two different rooms and the landing. I can't see any sensible way of lifting the floor as it is a chipboard floor and passes underneath the stud walls upstairs.
I definitely need to approach this from downstairs.
If the UB is infilled with wood and the joists are connected to this using joist hangers, how would I achieve the fire rating? Would the intumescent paint recommended by 'somebody' still be an appropriate solution?
Cheers,
Steve
Hi I can't think how you are going to acheive this without major distruption to to rooms and floors . Most things are possible with enough time and money , Having the beam underneath is a much simpler quicker / cheaper choice .
I must be over simplifying this in my head but the solution suggested by Fash seems perfectly simple and disruption free.
1) Prop either side of the wall 2) Cut joists 3) Put beam in place (infilled with timber) 4) Attach joists to beam using joist hangers.The only point I'm unclear on is fire protection...
Going off on a tangent here but does the beam need to be steel - what about Glulam? Wouldn't need fire proofing and the joists could be screwed directly to it using some kind of hanger?
Regards,
Steve
Another option is to have a plate welded to the bottom of the beam to pick up and support the old joists. You'd need your structural engineer to work this one out though.
It'll add a bit of cost to the fabrication, but save some time/effort on the actual install.
I was too :-) It seems most of the fire protection professionals want to maintain their status as guru's or something, most are quite reluctant to divulge their 'secrets'.
For example, I was quoted over £1,500 for intumescent paint to protect our steel beams, but no-one would say *why*. Once I learned "HpA", 3 sided, 4 sided etc, I found the same protection from Albisteel for £140. I know, that's crazy :-)
Our beams don't have any timber bolted directly to them so I don't have specific knowledge of this aspect, but my understanding is that.... - due to the different nature of wood/steel, any surface of the steel, fully covered by something like 50mm of timber is considered to have sufficient (30 minute or so) fire protection.
Timber generally chars before it burns, the char itself (carbonised wood or summat) protects the wood for some time prior to it actually failing, steel on the other hand, simply fails at a certain temperature.
Your local BCO will know how much timber is deemed satisfactory. So for example, if you go with your average universal beam with timber plated either side to pick up the joists you would need fire protection based on....
1: The HpA of the beam (this is a constant for the size of steel) 2: The number of exposed surfaces (in this case, two) 3: The length of time of protection required (30 mins in an average house) 4: The type of fire involved (cellulosic or hydrocarbon) - hydrocarbon for a dwellingYou would apply an intumescent paint to the relevant thickness accordingly, or use a certain thickness of fireboard, plaster board etc etc.
To calculate the HpA
1: measure or calculate the perimeter/circumference of the beam (in metres). 2: Calculate the section area (ie the surface area of the end of the beam in square metres). 3: Divide the circumference (in m) by the section area (in m2).Ie, 150x90 PFC24 has an HpA of (as near as dammit) 200.
Look at the 'Application Rates' table on the Albi site, and you'll see how much paint you need to put on.
Hth Someone
I doubt you could use *hook over* hangers.
Speaking agriculturally..... why not dispense with the upper flange? Perhaps back to back bolted unequal angle? Or two opposing T sections fishplated together.
One can revel in the freedom of an industry not regulated by building control:-)
regards
Yes you can still use intumescent paint. My BCO was quite happy with intumescent paint before the timber infill. The timber has a relatively low char rate and insulates the steel anyway. Clearly in this case you need to apply the paint before the timber is in position. In my case we painted the beam then fitted the infill timber and then lifted the beam into place.
For joist fixing, using face hangers or hangers which go over the beam depends on the wall above. If it's a stud wall then it may be easier to use face hangers as then the sole plate for the wall doesn't necessarily need to come out. The one case where I used face hangers the wall above was timber frame with brick infill (georgian construction method). In the case where I used over hangers the wall was simple brick and after needling it for support we took a few bricks (some of them fell out anyway) to get the hangers through.
Fash
Sod glulam, just makes a pain of the section and the BCO will probably not like it. See previous post about fire protection. Basically protect the steel as you would need to without the timber infill (probably 2 coats of paint) and the timber helps.
Regarding welding a flange to the bottom of the beam, I've tried that as well! (in total there are now 9 new pieces of steel holding up the house that weren't there when I moved in. This was my cellar span which is 3.6m with no walls on top (floor loading only). Again flat ceiling required but in this case joists are exposed underneath. The flange was more expensive, but looks much neater given that in this case it's exposed. In the situation where you want the flat ceiling in the room, it's also a bit of a pain trying to cover the 6mm (which is roughly what you would need) steel plate, unless you are overboarding the ceiling.
You shouldn't get too hung up on the fire protection. You only need to achieve 0.5hr protection since it's about making sure the building stays intact while everyone gets out. The reality is that in most cases the steel would actually survive for the required time with no protection. I'm not advocating doing nothing and the BCO would throw a wobbly, but if you coat it with intumescent paint x2 it will be fine. A google search for brush applied intumescent paint will find some suppliers.
Of course it's easier to sling the beam under, but you'll spend the next x years thicking "it really wouldn't have cost much more, damn." The extra costs are that it's more labour (cutting joists back fitting hangers etc.) and the support is a bit more difficult as you have to support the floor from underneath (easy) but any structures above also need to be supported to.
Fash
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